This application is related to the following commonly-assigned, copending applications, filed concurrently herewith, entitled: METHOD AND APPARATUS FOR AUTO-INCREMENTING THROUGH TABLE AND UPDATING SINGLE REGISTER IN MEMORY Ser. No. 08/993,834, METHOD AND APPARATUS FOR SCALING NUMBER OF VIRTUAL LANS IN A SWITCH USING AN INDEXING SCHEME Ser. No. 08/993,831, METHOD AND APPARATUS FOR CAPTURING SOURCE AND DESTINATION TRAFFIC Ser. No. 08/993,884, METHOD AND APPARATUS FOR MANAGING BIN CHAINS IN A MEMORY Ser. No. 08/993,826, APPARATUS AND METHOD FOR GENERATING AN INDEX KEY FOR A NETWORK SWITCH ROUTING TABLE USING A PROGRAMMABLE HASH FUNCTION Ser. No. 08/992,795, METHOD AND APPARATUS FOR CREATING A PORT VECTOR Ser. No. 08/993,044, SHARED ADDRESS TABLE WITH SOURCE AND DESTINATION TWO-PASS ALGORITHM Ser. No. 08/993,048, and METHOD AND APPARATUS FOR MANAGING LEARNING IN AN ADDRESS TABLE IN A MEMORY Ser. No. 08/994,691.
The present invention relates to network communications and more particularly, to a network switch utilizing two data forwarding models.
In computer networks, a plurality of network stations are interconnected via a communications medium. For example, Ethernet is a commonly used local area network scheme in which multiple stations are connected to a single shared serial path. These stations often communicate with a switch located between the shared data path and the stations connected to that path. Typically, the switch controls the communication of data packets on the network.
One arrangement for generating a frame forwarding decision uses a direct addressing scheme, where the network switch includes a fixed address table storing switching logic for the network. Such arrangements with fixed address tables may not support data transmissions from stations that utilize virtual local area network (VLAN) tagging as well as transmissions from stations that do not utilize VLAN tagging. In addition, such arrangements, with fixed address tables are often unable to support more than a single data forwarding model to generate data forwarding decisions.
There exists a need for a switching device that generates frame forwarding information for various types of data transmissions, including transmissions that utilize VLAN tags.
There is also a need for a switching device that supports more than one data forwarding model to generate data forwarding decisions.
These and other needs are met by the present invention, where the network switch supports more than one data forwarding model to generate data forwarding decisions. In a first data forwarding model, the switch supports learning user addresses for the network. In a second data forwarding model, the switch supports learning user addresses for data frames received from certain ports only. In addition, both the first and second models incorporate VLAN associations to generate the data forwarding decision.
According to one aspect of the invention, a network switch is configured for controlling the communication of data frames between stations. The switch includes a receive device for receiving data frames with each frame including a source address. The switch also includes a table that stores address information including data forwarding information and source addresses. The switch further includes a control device that is configured to operate in one of a plurality of modes with each of the plurality of modes utilizing virtual local area network (VLAN) information. The control device r e c e i v e s information from the receive device and searches the table for the data forwarding information based on the received information and the mode of operation of the control device.
Another aspect of the present invention provides a method for generating data forwarding information. The method includes configuring a multiport switch to operate in one of a plurality of modes. The switch controls the communication of data frames between stations and includes an address table. The address table stores address information, virtual local area network information and source addresses. The method also includes receiving information from a data frame and searching the address table for data forwarding information based on the received information and the mode of operation of the switch.
Other objects and advantages of the present invention will become readily apparent to those skilled in this art from the following detailed description. The embodiments shown and described provide illustration of the best mode contemplated for carrying out the invention. The invention is capable of modifications in various obvious respects, all without departing from the invention. Accordingly, the drawings are to be regarded as illustrative in nature, and not as restrictive.